Containers and more specifically metallic beverage containers are typically manufactured by interconnecting a beverage can end closure on a beverage container body. In some applications, an end closure may be interconnected on both a top side and a bottom side of a can body. More frequently, however, a beverage can end closure is interconnected on a top end of a beverage can body which is drawn and ironed from a flat sheet of blank material such as aluminum. Due to the potentially high internal pressures generated by carbonated beverages, both the beverage can body and the beverage can end closure are typically required to sustain internal pressures exceeding 90 psi without catastrophic and permanent deformation. Further, depending on various environmental conditions such as heat, over fill, high CO2 content, and vibration, the internal pressure in a typical beverage can may at times exceed 100 psi.
Thus, beverage can bodies and end closures must be durable to withstand high internal pressures, yet manufactured with extremely thin and durable materials such as aluminum to decrease the overall cost of the manufacturing process and the weight of the finished product. Accordingly, there exists a significant need for a durable beverage can end closure which can withstand the high internal pressures created by carbonated beverages, and the external forces applied during shipping, yet which is made from durable, lightweight and extremely thin metallic materials with geometric configurations which reduce material requirements. Previous attempts have been made to provide beverage can ends with unique geometric configuration in an attempt to provide material savings and improve strength. One example of such a beverage can end is defined in U.S. Pat. No. 6,065,634 To Crown Cork and Seal Technology Corporation, entitled “Can End and Method for Fixing the Same to a Can Body” (hereinafter the '634 Patent) and depicted as prior art in FIG. 2. In the beverage can end described in the '634 Patent, a chuck wall is provided which is inclined inwardly toward a countersink at an angle of between about 40° and 60°. The beverage can end closure described in the '634 Patent does not utilize standard double seaming processes which are well known in the industry.
Other patents have attempted to improve the strength of container end closures and save material costs by improving the geometry of the countersink region. Examples of these patents are U.S. Pat. No. 5,685,189 and U.S. Pat. No. 6,460,723 to Nguyen et al, which are incorporated herein in their entirety by reference. Another pending application which addresses the manufacturing processes utilized to produce various embodiments of the end closure of the present invention is described in pending U.S. patent application Ser. No. 10/107,941, which was filed on Mar. 27, 2002 and is further incorporated herein in its entirety by reference.
The following disclosure describes an improved container end closure which is adapted for interconnection to a container body and which has an improved countersink, chuck wall geometry, and unit depth which significantly saves material costs, yet can withstand significant internal pressures.